1. Field of the Invention
This invention pertains to access windows and similar equipment and more particularly to access windows for drive-through fast food service.
The invention especially relates to access windows typically installed on the side of a building adjacent a driveway to facilitate business transactions between a clerk and a customer. The most common use of such windows is for fast-food drive-in establishments.
In a typical commercial environment a drive-in access window must easily permit the clerk to transact business with a customer and yet provide the necessary isolation between the outside environment and the inside environment to satisfy health code requirements.
2. Brief Description of the Prior Art
Prior art access windows typically employ rigid inflexible members on the window openers such as those illustrated and described in U.S. Pat. No. 4,411,102. The windows may be actuated solely by manual force or by electrical motors triggered by such force. In both cases, however, the mechanisms involved rely on mechanisms which transmit forces with essentially no give or flexibility.
The prior art also describes an attempt to employ rigid members in combination with a rubber-toothed transmission belt. An example of such a system is described in U.S. Pat. No. 4,442,630.
The manually-operated service windows depicted in the prior art referred to above typically make use of a plunger head with limited surface area for contact by a human operator. The use of such a plunger head in combination with other mechanical aspects of the prior art has resulted in a window which requires substantial force to open, and which requires a significant amount of force to retain it in the open position. In the case of a purely mechanical system, the window requires considerable effort on the part of a clerk to open a window and keep it open.